math: fix scalbn and scalbnf on overflow/underflow

[musl] / src / math / scalbnf.c

diff --git a/src/math/scalbnf.c b/src/math/scalbnf.c
index 243dafd..e5c76db 100644 (file)
--- a/src/math/scalbnf.c
+++ b/src/math/scalbnf.c
@@ -2,6 +2,8 @@
 
 float scalbnf(float x, int n)
 {
+       /* make sure result is stored as double on overflow or underflow */
+       volatile float z;
        float scale;
 
        if (n > 127) {
@@ -10,8 +12,10 @@ float scalbnf(float x, int n)
                if (n > 127) {
                        x *= 0x1p127f;
                        n -= 127;
-                       if (n > 127)
-                               return x * 0x1p127f;
+                       if (n > 127) {
+                               z = x * 0x1p127f;
+                               return z;
+                       }
                }
        } else if (n < -126) {
                x *= 0x1p-126f;
@@ -19,10 +23,13 @@ float scalbnf(float x, int n)
                if (n < -126) {
                        x *= 0x1p-126f;
                        n += 126;
-                       if (n < -126)
-                               return x * 0x1p-126f;
+                       if (n < -126) {
+                               z = x * 0x1p-126f;
+                               return z;
+                       }
                }
        }
        SET_FLOAT_WORD(scale, (uint32_t)(0x7f+n)<<23);
-       return x * scale;
+       z = x * scale;
+       return z;
 }